This is an artist's conception of the river turtle Boremys, which is one of the first known species whose existence actually improved in the immediate aftermath of the massive extinction event, 65 million years ago.

Walter Joyce of the University of Tubingen's Institute for Earth Sciences explains just how Boremys did so well for itself:

"We believe that aquatic turtles were particularly resilient to the meteorite impact because they naturally possess a wide behavioral repertoire that allows them to survive bad times. When it gets too cold, aquatic turtles naturally will hibernate. When it gets too hot or dry, aquatic turtles will estivate (dig themselves into mud holes and wait out the problem). These are tools that come in handy during regular times, but apparently also during meteorite impacts."

This turtle is one of a number of species that briefly filled the void left behind the dinosaurs, who were completely wiped out along with many birds and marine species in the wake of the massive meteor impact. Boremys was small, with a shell that was on average only about 9.8 inches long. Its jaw suggested that it could eat just about about anything from plants to fish, which would have probably come in handy as the rest of the world went through chaotic upheaval and food resources became less than dependable.

Joyce continues:

"While large land animals must have dropped dead by the hundreds, it appears that many small to medium-sized aquatic amphibians, such as frogs and salamanders, as well as reptiles (turtles, the crocodile-resembling champsosaurs, actual crocodilians, and lizards) generally did well, likely because all of these groups naturally have techniques that help them to survive bad times."

So why did Boremys ultimately die out? It appears that this species, along with many other ancient turtle species, could not retract its head inside its shell when threatened like its modern counterparts. That would have left it vulnerable to attack, and the emergence of mammals in the Tertiary period is probably what ultimately did in this shockingly resilient species.